Tag Archives: ubuntu

06 May
2010

Thoughts on OggCamp in Liverpool

Last weekend I went to Liverpool (my first visit there!) to attend OggCamp for the second year in a row. This isn't a part of the software community I normally interact with, but I accidentally went to a LUGRadio event once a couple of years ago and have been hooked ever since!! OggCamp went to 2 days for the first time this year and was a triumph of organisation, with a great venue and a wonderful feel to the whole event. I was particularly impressed (as an event organiser myself) that for an event with no registration, they had the right number of chairs, the venue was the right size, but in fact they didn't have that information so a very well done to whoever made that call :)

I spoke again this year, it seemed to me like since there was voting on the talks, if my talk wouldn't be a good fit then I wouldn't get a slot! So I did put in a talk about source control; a topic that I'll be speaking on in a couple of weeks at TEK-X in Chicago and one that I still feel a little bit wobbly about. Taking the main stage to give a hastily-reduced version of the talk to such a well qualified audience and coming off the stage to feel like it went OK was an excellent preparation for my next speaking event and I got chatting to all sorts of people while I was there. I'm not really a linux nut but I do have ubuntu or kubuntu installed on everything, and it was great to hear a bit more about so many aspects of technology that I use but don't know much about.

The event ended in the traditional live podcast with all the presenters of Linux Outlaws and the Ubuntu UK Podcast all on stage at once. This is always good fun and there were some laughs from the crowd as always.

OggCamp Live Podcast

All in all, a great event, and I'm very much looking forward to next year's!

26 Apr
2010

Bzr-svn: Preserving Commits and Rebasing

Recently I've been using bzr-svn when I'm working with subversion repositories; its a bridge between a local bzr repository and a remote subversion one. I travel fairly frequently and the pain of being disconnected from the server, unable to diff or log, and then either unpicking everything I've done or sending a monster commit with the message "Things Lorna did in the last 2 days" is just tedious and annoying. Possibly more tedious and annoying for the rest of the team than me even, so a better solution is more than welcome!

Some time ago I blogged about starting to use bzr-svn but its taken me a while to get past those first steps. Having the repo locally is so fast to use, and the speedy diff and log functionality had me completely sold straight away. I've been mildly annoyed by bzr squashing my commits though, meaning that I'm still doing a single monster commit to subversion when I come back online after being gone for a few days.

Today, with some help from the very lovely people in the #bzr channel on freenode, I found out how to preserve my commit history when sending the changes back to subversion from bzr-svn. The bzr-svn user guide recommends a particular set of commands, but this includes merging your changes into the mirror of SVN. Even in a standard bzr branch, this would show in the logs as a single, combined commit.

Push, Don't Merge

The key to retaining the commit history is to push changes from the branch, rather than merging into the trunk mirror. To make this clearer, I've shown an example. The SVN is checked out into lorna-trunk and I'm making changes in the lorna-branch directory, including adding the db directory and the hello.php file.

$ bzr commit -m "initialising database files and hello.php"
Committing to: /home/lorna/data/personal/publish/tek10/svn_vs_distributed/bzr-svn-example/lorna-repo/lorna-branch/
added db
added hello.php
added db/setup.sql
Committed revision 2.
$ bzr push ../lorna-trunk/
All changes applied successfully.
Pushed up to revision 2.

No matter how many times you commit, when you push, all your changes will be sent to subversion as individual commits in the same way. This will really help me next time I'm offline for a little while!

When There Are Changes In Subversion

Charmingly, while answering my questions to get me this far, the #bzr channel inhabitants then immediately explained to me that to handle changes in subversion, I'd have to rebase my branch before I could push my changes. This is because you can only push to a branch that is in sync with where yours was when you started making changes. If you try to push to subversion when there are changes in it, you will see this error:

bzr: ERROR: These branches have diverged.  See "bzr help diverged-branches" for more information.

All I needed to do was to run bzr update in the mirror, and then rebase my branch onto that. At first my system didn't recognise the rebase command, but this was because I needed to install the bzr-rebase package (called bzr-rewrite in newer versions but bzr-rebase in mine, Ubuntu 9.10 Karmic Koala). Rebasing was easy to do and brings the changes from the repo into your working branch. Here are the commands and how the output looked for me (with shortened paths to make this more readable):

lorna@taygete:~/.../lorna-branch$ cd ../lorna-trunk/
lorna@taygete:~/.../lorna-trunk$ bzr update
+N  readme
All changes applied successfully.
Updated to revision 3.
lorna@taygete:~/.../lorna-trunk$ cd ../lorna-branch/
lorna@taygete:~/.../lorna-branch$ bzr rebase ../lorna-trunk/
All changes applied successfully.
Committing to: /home/lorna/.../lorna-branch/
modified hello.php
Committed revision 4.
lorna@taygete:~/.../lorna-branch$ bzr push ../lorna-trunk/
All changes applied successfully.
Pushed up to revision 4.

I haven't had a lot of experience with using this in difficult situations with complex branching or conflicts yet, if you have any tips to add though, a comment would be excellent :)

19 Feb
2010

Open Office Presenter Console

I've been having issues with the presenter console on both my ubuntu machines since upgrading to Karmic (9.10). One is a Thinkpad T400 running kubuntu and the other is an aspireone netbook running ubuntu netbook remix. Neither wanted had a working installation after upgrade and I couldn't get the plugin installed using the open office plugin manager.

I discovered that this plugin is now available through apitude - simply install the package openoffice.org-presenter-console and it should all work splendidly! I use the presenter console when I am speaking (which is quite often) to show the time and the upcoming slide, its a great tool.

15 Jan
2010

Screen in Ubuntu Karmic

I have written about screen quite often, mostly including my .screenrc file and showing how to have named tabs for the various screen tabs you have open. When Ubuntu Jaunty came out, I found it had some quite cool enhancements that made the customisations for screen really easy by default - and I wrote about these.

In Karmic Koala, Ubuntu 9.10, the packages are still there but they've changed names! So if you want to use screen with Ubuntu Karmic or later, install packages byobu and byobu-extras, and uninstall screen-profiles and screen-profiles-extras (they were broken on my system after upgrade anyway) and you should find everything works as expected. To run screen with the new features, you should run "byobu" instead - although screen commands seem to work to detach and reattach the screens that result, weirdly.

I'm mostly posting about it because I have been very frustrated and there's no way I could have guessed, or probably ever will remember, what these packages are called. Apparently a byobu is a japanese room screen ... you learn something new every day!

15 Dec
2009

Sound Issues with Kubuntu Karmic Koala

Since upgrading my work machine to karmic koala, I've noticed that my sound had stopped working. There were some broken packages in aptitude and Skype knew there was a problem as it notified me when I tried to make a call. I saw some issues reported with karmic, notably this one, so I uninstalled pulseaudio

sudo aptitude remove pulseaudio

When I restarted Skype, everything seemed to work as expected - for reference I have a thinkpad T400, if you're having the same issues, then hopefully this will help!

11 Aug
2009

Customising Screen-Profile Files

I wrote a while ago about the new version of screen in Ubuntu Jaunty. Screen is an application which lets you run lots of tabs inside one terminal window, then disconnect from screen and reconnect again later. You can turn on and off a whole bunch of notifications which appear inside screen, and I also added the pink tabs I used with older versions of screen.

The tabs line is the one in the profile file which starts "caption always".

caption always "%{wk}%H%{Bk}|%{Mk}%?%-Lw%?%{km}[%n*%f %t]%?(%u)%?%{mk}%?%+Lw%? %=%{Bk}"

I also altered the "hardstatus string" line, which holds lots of placeholders, to remove the clock - I run screen on my laptop inside KDE mostly, so I already know what time it is. Annoyingly this isn't customisable via the menus but I edited my profile file to get rid of it - here's the diff

29c29
< hardstatus string '%99`%{= kw} %100`%112`%= %102`%101`%114`%115`%108`%113`%119`%117`%118`%116`%106`%104`%103`%105`%107`%Y-%m-%d %0c:%s'
---
> hardstatus string '%99`%{= kw} %100`%112`%= %102`%101`%114`%115`%108`%113`%119`%117`%118`%116`%106`%104`%103`%105`%107`'

The only thing annoying me now is that screen seems to constantly redraw itself, so Konsole thinks there is activity in that screen, when there isn't. Suggestions on stopping this or more ways you can customise your screen file are gratefully received - just add a comment!

21 Jul
2009

Ubuntu Netbook Remix on Aspire One

A while ago, actually quite a while ago in May, I put the Ubuntu Netbook Remix version of Ubuntu 9.04 Jaunty Jackalope onto my lovely blue Acer Aspire One netbook.

The way this works is that on another machine (or I guess on an existing OS on the netbook) you download a bootable USB key image. With some trepidation (not a whole lot, I did back up first), I put in the USB key and settled in to see how far I could get with the installation.

Well, a short time later I realised I'd finished installing and was really just fiddling! Straight out of the box the wifi worked, the hibernate worked, sound (in and out) worked, the webcam worked, and there is this great window handler thing which amalgamates title bar and task bar into one. There's also a cute menu on the desktop - all in all its really neat:

The working hibernate in particular has really made a big difference, at home the netbook just gets used for short bursts and lives next to my bed, usually plugged in. When it comes into its own though is at conferences! I can flip this thing open, use it, and flip it shut, pretty much all day. The startup time is really small from suspend and so long as I'm only dipping in and out (at conferences, I'm mostly in talks so I'm only ever checking mail etc), the battery life easily lasts a day.

Thanks to the Ubuntu folks - this is one quality piece of software and now I love my little netbook even more. Anyone else using the netbook remix? Were your experiences as good as mine?

11 May
2009

Presenting Under Linux: xrandr

This is a mini-primer on using xrandr to configure a second screen under Linux, but first I'll start with some background.

I've been a linux user for a few years now but when I started working for Ibuildings I started giving presentations, either as a speaker or when delivering training - and for a long time I used to boot into Windows for those, using a VM if I needed to code.

The main reasons I wasn't comfortable using Linux to present were:

  • I have Powerpoint and I use the presenter view a lot
  • Linux doesn't automatically find and configure monitors like Windows can.

Since Ubuntu Intrepid Ibex (8.10), its been possible to reconfigure screen in Linux without restarting X. But I was kind of scared of xrandr and I still liked the Powerpoint presenter view so I just carried on with windows. Then I realised that Open Office had also released a presenter view and I gave it a try. With one obstacle removed it was time to learn to work xrandr, which means I can also work external monitors without fiddling with xorg.conf, very useful. I'm now pretty confident with it so here's the benefit of my wisdom*

xrandr

The first thing to do is figure out what you have and what your options are. So plug in the second screen and run xrandr with no arguments. On my system I get something like this:

Screen 0: minimum 320 x 200, current 1024 x 768, maximum 2560 x 1024
VGA connected 1024x768+0+0 (normal left inverted right x axis y axis) 338mm x 270mm
   1280x1024      60.0 +   75.0
   1024x768       75.0*    60.0
   800x600        75.0     60.3
   640x480        75.0     59.9
   720x400        70.1
LVDS connected 1024x768+0+0 (normal left inverted right x axis y axis) 304mm x 190mm
   1280x800       60.0 +   50.0
   1024x768       85.0     75.0*    70.1     60.0
   832x624        74.6
   800x600        85.1     72.2     75.0     60.3     56.2
   640x480        85.0     72.8     75.0     59.9
   720x400        85.0
   640x400        85.1
   640x350        85.1
HDMI-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 disconnected (normal left inverted right x axis y axis)

This shows VGA (your external output) and LVDS (the laptop screen) and all the various modes they support. I sometimes see output under HDMI-1, and this seems to cause problems so I always turn off this output by running:

xrandr --output HDMI-1 --off

Next I send a command to set the resolutions on both screens. For projectors I tend to go with 800x600 as this almost always works and it means the text on my laptop screen is then so large I can see it from several feet away!

xrandr --output LVDS --mode 800x600 --output VGA --mode 800x600

Its perfectly fine to have different resolutions on both machines but bear in mind that X has one desktop and will show you sections of it on each monitor so if they're different sizes you sometimes get either bits missing off one monitor or one of the outputs looks stretched. I don't really have any general advice with this other than get the projector in the right ratio and then fiddle with the available modes to see what works for you.

To set the second screen to be different from the first (i.e. tiled rather than mirrored), just tell xrandr where you want it.

xrandr --output LVDS --mode 1280x800 --output VGA --mode 1024x768 --right-of LVDS

Again you'll get sections of a single desktop, not two separate areas, so things might look odd if they are on both screens. For me this command has worked really well since I got to grips with it in the last few months, and I've plugged various machines in to various external monitors and given a few different talks. I'm sure there is a lot more to know about xrandr but I haven't needed it yet - hope this is helpful! If you have any experiences with this or anything to add, just drop a line into the comments form.

* I'm not an expert by any means, but the above works for me on Ubuntu with my Thinkpad T400 and my Acer Aspire One.